BYOJeopardy is a program to create and play Jeopardy-like games. BYOJeopardy helps you easily build and display jeopardy games. Also, you can export boards to html, so you can play anywhere. This a great tool to use for reviewing topics in the classroom.

phpSudoku is a small and fast script for a sudoku online-game on your website. It includes 200000 sudoku puzzles and ist very easy to integrate in every website and your existing webdesign. It requires PHP 4 or higher. There is no need of MySQL.
The latest release of php Sudoku with 1.000.000 puzzles is hosted at https://github.com/msoftware/phpsudoku. On sourceforge.net you will only find php sudoku V 1.0. All newer versions are available at https://github.com/msoftware/phpsudoku.

The Project wants to give a fast and well-designed solver for the famous sudoku-game with PHP/JavaScript based on the AJAX-technology. As a second step it is planned to implement a sudoku-generator too.

A PHP word search script. It has many options, including the ability to use different shapes for your puzzle, or you can design your own shape. Then you can either print the puzzle or play it online. The script supports many different languages.

This is a module for PHP Nuke open source Content Management System (CMS) that allows webmasters to publish interactive Crosswords on their websites.
Features:
:: Last Crossword direct access
:: Interactive crosswords List
:: Elapsed time record
...

PHPAdventure! is an interactive fiction engine written in PHP that allows game programmers to easily create point-and-click web based text adventure games. May 2006: I'm not maintaining this anymore. If you want to take it over, let me know.

Enjoy doing the crossword in the morning? But your paper doesn't print one on Sundays! Why not store the old crosswords in your computer so you can replay them anytime. Crosswordsaver keeps them in a database, you can play them later from your browser.

Cryptomak contains cipher and tools for encryption utility written in php such as substitution, vigenere, affine, transposition and index of coincidence. It is powered by Phrame platform which implements MVC design and Smarty template engine.

Darkness is Spreading is a remake of Flood-it type game. It is an open source and free game written in PHP. It should be hosted on a server able to process PHP and the levels are pretty easy to add on to.